普及练习场 动态规划的背包问题 开心的金明

题目链接

题意理解

这题只要把价格乘以重要度，就变成了01背包。然后01背包是有套路的。

代码

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
    static int N, m;
    static final int maxn = 40;
    static int[] v = new int[maxn];
    static int[] w = new int[maxn];
    static int[][] dp = new int[maxn][30010];
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        N = fs.nextInt();
        m = fs.nextInt();
        for(int i = 1; i <= m; i++) {
            v[i] = fs.nextInt();
            w[i] = fs.nextInt();
            w[i] *= v[i];
        }
        for(int i = 0; i < m + 1; i++) {
            for(int j = 0; j < N + 1; j++) {
                dp[i][j] = 0;
            }
        }
        int max = -1;
        for(int i = 1; i <= m; i++) {
            for(int j = 1; j <= N; j++) {
                if(j >= v[i]) {
                    dp[i][j] = Math.max(dp[i-1][j], dp[i-1][j-v[i]] + w[i]);
                } else {
                    dp[i][j] = dp[i - 1][j];
                }
                if(dp[i][j] > max) {
                    max = dp[i][j];
                }
            }
        }
        System.out.println(max);
    }
    public static class FastScanner {
        private BufferedReader br;
        private StringTokenizer st;

        public FastScanner() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        public String nextToken() {
            while(st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (Exception e) {
                    // TODO: handle exception
                }
            }
            return st.nextToken();
        }

        public int nextInt() {
            return Integer.valueOf(nextToken());
        }
    }

}